Engine starter



June 10, 1941. DYER 2,245,438

- ENGINE STARTER Original Filed July ,6, 1956 3 Sheets-Sheet -l June 10,1941. DYER 2,245,438

' ENGINQ STARTER Original Filed July 6. 1956 3 Sheets-Sheet 2 June 10,1941. Y 2,245,438

ENGINE STARTER Original Filed July 6, 1936 3 Sheets-Sheet 5 PatentedJune 19, 1941 ENGINE STARTER John B. Dyer, Dayton, Ohio, assignor toGeneral Motors Corporation, Detroit, Mich.', a corporation of DelawareApplication July 6, 1936,.Serial No. 89,090 Renewed May 15, 1939 28Claims.

This invention relates to apparatus for starting internal combustionengines and more particularly to the apparatus disclosed in my pendingapplication Serial No. 52,947, filed December 5, 1935.

The objects of the invention disclosed in my said application arechiefly to provide an engine starter which is eficient, durable andquiet in operation and which is economical to construct; According tothe embodiment of my invention disclosed in said application theseobjects are accomplished by providing a friction drive between theengine to be started and the starting motor, said drive comprising adisc or annular flange associated with the engine fiy-wheel or othermember connected with the engine crank shaft and a pair of driving discswhich are engageable with opposite faces of the driven disc. Eachdriving disc has an independent driving connection with the startingmotor shaft. Each of said independent driving connections includescamming members so constructed and arranged that when a driving disc hasbeen brought into engagement with the driven disc, rotation of the motorshaft will force the driving disc against the driven disc with pressuresufficient for driving engagement between the motor and driven discwhereby the motor will crank the engine. Each of said independentdriving connections is so constructed that, when the engine becomesself-operative, the

driving pressure will be relieved to release the engine from thestarting motor so that theengine will not drive the motor at anexcessive speed.

The objects of the invention disclosed in the present application are tocompel each disc of I the pair of driving discs to do its share of workin driving the driven disc associated with the engine to be started. Ihave found, with respect to the models of engine starters disclosed inmy said co-pending application, that there is a tendency for one of thediscs to assume the burden of driving the driven disc while the otherso-called driving disc may slip on the edge of the driven disc and exerta driving effort upon the driven disc less than that applied by thefirst mentioned driving disc. The result of this is that the sides ofthe driven disc do not wear evenly and one of the driving discs whichassumes the major portion of the work of driving is worn away morerapidly than the driving disc which exerts lesseffort. This unevenwearing away of the driving surfaces results in less efifective drivingengagement after the wear has continued beyond a certain degree. In thepresent invention I overnection between the two driving discs of such anature that both discs are compelled to exert substantially the samedriving pressure on the opposite faces of the driven disc. In order toaccomplish this object the disclosed embodiment of the present inventionincludes the combina- "tion with the driven disc associated with theengine to be started, a pair of driving discs which are engageable withopposite faces of the driven disc, an independent driving connectionwith the starting motor and each driving disc, each independent drivingconnection including camming members so constructed and arranged thatwhen a driving disc has been brought into engagement with the drivendisc, rotation of the motor shaft will force the driving disc againstthe driven disc with pressure sufficient for driving engagement betweenthe motor and the driven disc, and an interconnection between the twodriving discs so constructed and arranged that the tendency of a drivingdisc to assume a greater share of the work of driving will concurrentlycause the other driving disc to have a similar tendency whereby the twotendencies are equalized and each disc assumes its burden of driving.

The present invention includes means operating independent of the motorfor causing the driving discs to engage the driven disc before the motoroperates. As will be'more apparent hereinafter, the shock or abnormalstrain attendant upon establishment of connections between the startingmotor and the engine has been minimized, and, consequently, theoperation of the starter drive mechanism has been made more quiet, sothat the durability as well as reliability of the starter drivemechanism has 7 been greatly improved.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of one form of the presentinvention is clearly shown. In the drawings:

Fig. 1 is a side view partly in section showing a preferred embodimentof the invention in its normal condition.

Fig. 2 is a wiring diagram thereof.

Fig. 3 is a fragmentary longitudinal sectional view of a startingapparatus.

Figs. 4, 5, 6 and 7 are sectional views taken respectively on the lines4-4, 55, 6-6 and l'l of Fig. 3.

Fig. 8 is a development of the outer ball race.

Fig. 9 is a development of the inner-ball race.

Figs. 10, 11 and 12 are diagrammatic views similar to Fig. 3 but showingthe mechanism in diiferent positions of operation.

The motor 29 for starting the internal combustion engine is preferablyan electric motor comprising field frame 2| associated with an end frame22 and a housing 23 which carry bearings 24 and 25, respectively, forthe motor armature shaft 26 which carries an armature 27.

Referring now particularly to Figs. 3 to '7 the shaft 26 carries atubular shaft 30 which is splined at 3| to the shaft 26 so that thetubular shaft 30 is at all times drivingly connected with the shaft 26but may slide thereon to a limited extent. The tubular shaft 30 is urgedtoward the right by spring 32 which surrounds the armature shaft 26 andwhich bears against parts to be described later which are associatedwith the shaft 3|].

The driven disc connected with the engine to be started is designated bythe numeral 35. Disc 35 is engaged by axially movable driving discs 33and 34 located respective adjacent opposite faces of the driven disc butnormally separated therefrom as shown in Fig. 3. Each of the drivingdiscs 33 and 34 has an independent driving connection with the shaft 33,said driving connection being so constructed and arranged that, afterthe driving discs have been moved against the driven disc 35, rotationof shaft 33 by the motor will cause the driving discs to be pressedagainst the driven disc with pressure sufficient for engine startingpurposes and that, after the engine has become self-operative, thepressure between the driving discs will be relieved so that the enginewill not drive the starting motor. Each of these driving connectionsbetween the driving discs and the shaft 38 comprises camming members,preferably cooperating screw threads which are separate and independentof each other.

The driving connection between the shaft 30 and the driving disc 33comprises a left-hand screw thread connection which includes a helicalroll of balls 36, held in spaced relation by a ball retainer 31 havingspirally arranged holes 38 as shown in Fig. 9, and received by inner andouter ball races 36a. and 361) provided respectively by the tubular hub33a of the driving disc 33 and the tubular flange 33a of the shaft 30.

The driving connection between the shaft 39 and the driving disc 34 is aright-hand screw thread connection of the same lead as that of theleft-hand screw thread connection, which connects the shaft 36 with thedriving disc 33. This right-hand screw thread connection comprises ahelical roll of balls 38 which are retained in spaced relation by a ballretainer 39 having a helical series of holes 40 as shown in Fig. 8.These balls 38 cooperate with inner races 38a and 381) providedrespectively by the shaft 33 and a tubular member 4!, which is attachedto the driving disc 34 by providing the latter with spaced notches 42which receive tangs 43 extending from the main cylindrical portion ofthe member 4|, said tangs being swedged so as to fit tightly into thenotches 42 as shown in Fig. 7.

The driving disc member 34 has an internally splined portion 44 which isthe complement of the externally splined portion 45 of the tubular hub33a of the driving disc 33. These cooperating splines 44 and 45constitute an equalizing interconnection between the driving discs 33and 34 of such nature that each driving disc is compelled to assume itsshare of the burden of the driving of the driven disc 35.

It will be noted that the screw thread connections between the drivingdiscs and the shaft 30 are opposite in pitch so that, after these discshave been moved into engagement with the driven disc 35 rotation of themotor shaft 30 will cause each driving disc to be wedged independentlyagainst the driven disc with a pressure sufiicient for engine startingpurposes, and so that, after the engine becomes self operative and thedriven disc 35 attempts to rotate the driving discs 33 and 34 fasterthan they can be rotated by the starting motor, the driving pressurebetween the driving discs and the driven disc will be relieved so thatthe engine cannot drive the starting motor at excessive speed.

The present invention includes a means independent of the starting motorfor causing the driving discs 33 and 34 to be moved into engagement withthe driven disc 35 before the starting motor operates to cause thedriving discs to be wedged against the driven disc with pressuresufficient to transmit torque sufficient for engine starting purposes.This means for causing a preliminary engagement of the driving discswith the driven disc will now be described.

The tubular sleeve member 4| is provided externally with a plurality ofsplines 5| adapted to be engaged by the internally splined flange 52 ofan actuator sleeve 53 which is supported by a disc 34 secured near theleft hand end of shaft 30 by a nut 48. Disc 54 has tongues 51 bearingagainst the left hand ends of grooves 58 extending longitudinally andprovided in diametrically opposite portions of the sleeve 4|. A dishedwasher 55 is located against the flange 49 of the sleeve 53 and receivesthe pushing effort of spring 32 which serves to maintain the relativelocation of the sleeve 53 and the member 4| as shown in Fig. 3, that is,with the tongues 51 bearing against the left hand ends of grooves 58.The spring 32 serves also to maintain the driving discs 33 and 34normally spaced from the driven disc 35 as shown in Figs. 3 and 10, thedisc 33 abutting against the flanged end of bearing 25. The sleeve 53being longitudinally splined to the driving shaft 30, due to the greatmass of parts connected with the shaft 39 including the armature shaft25 and the armature 21, the shaft 30 tends to remain stationary as thesleeve 4| is moved longitudinally. Hence the sleeve 4| moveslongitudinally without rotating substantially. The pitch of the splines5| formed on the member 4| is such that, as the sleeve 53 is movedtoward the left from its position shown in Fig. 3, the disc 34 willrotate relative to the shaft 30 in such direction as to cause the disc34 to move into engage- 'ment with the disc 35.

In order that the sleeve 53 may be moved toward the left from itsposition shown in Fig. 3 it is provided with the external flange 49 forreceiving the ends 53 of a bifurcated lever 10 having at its upper endan elongated notch H which receives a pin 12 carried by bifurcatedbracket 13 integral with an L-shaped bracket 14 attached to anelectromagnet frame 15 mounted upon the motor frame 2|. A spring 16surrounds a stud Tl attached to the bracket 13 and urges the upper endof the lever it! against the pin 12.

The lever H3 is actuated electromagnetically by means which will now bedescribed with reference to Fig. 2. As shown diagrammatically in Fig. 2,magnet frame encloses electromagnet windings and 8| surrounding amovable solenoid armature 82 guided by the magnet frame 15 for slidingmovement toward a stationary core 83 which is located in the magneticcircuit of the electromagnet. The armature 82 is connected by a link 84with the lever 18. Armature 8-2 is associated with a rod 85 upon whichis mounted a non-conducting collar 88 yieldingly urged by spring 8'!against a shoulder 88, the spring 81 being confined between the collar86 and a Washer 88 held from movingtoward the right by a pin 98. Aspring 8i located between a stationary part 82 and the rod 85 normallymaintains the rod 85 and the armature 82 in the normal position as shownin Fig. 2.

The collar 86 carries a movable switch contact I 85' adapted to engagewith contacts 96 and 91 of the starting motor switch. Contact 98' isconnected by wire -98 with a switch terminal 99. Contact 9? is connectedwith the starting motor 28 which is grounded at I88. Terminal 9815connected with storage battery II grounded at I82. Terminal 98 may beconnected simultaneously with terminals I83 and I88 by a movable contact185. Terminal I85 is connected with contact I88 of an. automatic switchhaving also aterminal I8? connected with windings 88' and SI, 8 I beingconnected with contact 81 and 88 being grounded at I88. This automaticswitch designated in its entirety by numeral H8, comprises a suctionchamber Ill connected by pipe H2 with the intake manifold of an internalcombustion engine.

be moved into engagement with the driven disc 35; before operating thestarting motor 28. This is accomplished by means independent of' themotor, namely, the electromagnet means shown diagrammatically in Fig.2.. The manner in which the driving discs are caused to engage thedriven discs will. now. be described particularly with respect to Figs.10, 11 and 12.

To. start the, engine the operator turns the I switch contact I85 so asto causeit to engage the contact I83 and the contact I84. The ignitionis, then turned on, theignition circuit being connected with theterminal 58.3 whichisthen connectedwith the battery ii. The terminal I84being then also connected withbattery I8I, current will flow from thebattery I8I throughv the windings 88 and SI, the former being. directlygrounded at I88 and the latter being indirectly grounded through themotor 28. Theelectromagnet windings 38 and 8| being energized, thearmature 82 will move toward the left thereby causing the lever I8 tomove to swing toward the leftin a clock-wise direction around itspivotl2. During the movement of thelever T8 the contact. 95 will be movingtoward contacts 95 and 81; but before engagement of these contactsactually occurs, the driving discs 33 and 34 will be brought intoengagement with the driven disc 35 in a manner which will be apparentfrom a consideration of Figs. 10, 11 and 12.

As lever I8 moves toward the left the entire drive assembly will bemoved bodily toward the left from the position shown in Fig. 10 to thatshown in Fig. 11 thereby causing the driving disc 33"to engage thedriven disc 35. This movement of 'the drive assembly is resisted by thespring 32 which normally urges the shaft" 38" towardsthe bearing-25iFurther movement of the lever I8 toward the left causes the sleeve 53 tomove to the left relative to the tubular member n as shown in. Fig. 12,thereby causing the member M to be rotated in a counter-clock-wisedirection as viewed in the direction of the arrow 88 in Fig. 12. In thedisclosed embodiment of the invention the member AI isrotatedapproximately 45. When the member 4| rotates 45 or /a revolutioncounter-clockwise it efiects an axial movement of itself on the shaft 38and also effects a similar movement of the shaft 38 together with itselfalong the shaft. Both of these movements are toward the right and theirsum total is equal to the distance between the driving disc 34 and thedriven disc 35 as shown in Fig. 11. Assuming that the normal spacingbetween each of the driving discs and driven disc is of an inch as shownin Fig. 18, the spacing between the driving disc 34 and the driven. disc35 as shown in Fig. 11 will be of an inch. This 45 counter-clock-wiserotation of the member ll will cause members 4i and 34 to travel of aninch along the tubular shaft 38, this distance being the product of orrevolution and 7 of an inch which is the lead of the helical row ofballs 38. The 45 counterter-clock-wise rotation of the member 8| willimpart similar rotation to the tubular hub 83a of the drivingdisc 33since the parts 8i and 83a are connected together by the splines id and85. Since the. hub 33a cannot move axially, being restrained by theengagement of disc 33 with disc 35, the shaft 38 will move axiallytoward the disc 35 and carry'with it bodily'the sleeve 4i and disc 38 adistance which equals of the lead of the helical roll of balls 38, whichlead is 7 of an inch. The product of and equals 5 of aninch. The 7 of aninch Which the parts 4I and 34 move relative to the part 38 is added tothe 5/12 of an inch which the part 38 moves relative to the shaft 28making the movement of the part 34 relative to the shaft 25 a total of/134 of an inch.

The driving discs have now completed their preliminary movements intoengagement with the driven discs. Hence the starter drive hasbeenpre-conditionedfor operation by the electric mo,- tor. After the drivingdiscs have completed their preliminary movement the lower end of thelever 18 cannot move any further toward the left.

Continued motion of the solenoid armature 82 toward the left to closecontacts 95, 85 and 81 may take place by reason of the fact that thereis lost motion between the upper end of the lever 18 and the pivotbearing. '72. Just before these contacts are closed, the spring I8 isheld by the solenoid armature 82 under compression, so that yieldingpressure is applied between end 58 of lever I8 and the sleeve flange 89.Therefore, it is only after the driving discs have been brought intoengagement with the driven discs under yielding pressure that the motorswitch contact 95 is caused to engage the stationary contacts 88 and GT.When this occurs the motor 28 operates to turn the shaft 28. The windingSi is then short circuited and winding 88 only is effective to hold themotor switch closed. Winding 88 comprises preferably a large number ofturns of fine wire and winding 8| fewer turns of coarser wire. Bothwindings are required to effect movement of the armature 82 initiallytoward the core 83 but winding 88 only is required to maintain thearmature 82 in its'attracted position. The starting motor then willoperate to cause the'shaft'26 to rotate in a clockwise direction asviewedlooking in the direction of arrow 6% of Figs. 10, l1 and 12. Atthe instant the motor starts to turn the shaft 26, the driving discs 33and 34 being then in engagement with the driven disc 35, the firstaction is to increase the pressure between the driving discs and thedriven discs due to the cooperation of the screw thread connectionsbetween the driving discs and the motor shaft.

Thus in response to the operation of the electric motor in turning theshaft 26 the driving discs 33 and 34 are caused to press against thedriven disc 35 with pressure suflicient to insure a driving engagementbetween the electric motor and the engine for engine starting purposes.Hence the electric motor is drivingly connected with the engine and willstart the latter. This driving engagement has been effected noiselesslydue to the fact that means independent of the motor have been employedfor moving the driving discs against the driven disc before the motor isconnected with the current source. Then when the motor is caused tooperate it produces noiselessly a pressure between the driving anddriven discs sufficient for engine starting purposes.

It is practically impossible for one of the driving discs to be wedgedagainst the driven. disc-at a pressure greater than that of the pressureon the driven disc for the reason that two discs are tied together, withrespect to their axial movement, by the longitudinal splines 4:3 andwith which they are respectively provided. Therefore, in cranking theengine, each driving disc shares its burden of exerting driving pressureagainst the driven disc. Naturally, there is some wear on the surfacesof the driving and driven discs; and. this wear, though very small,increases with the use of the starter. When the starter drive embodiesthe feature of the present invention, both driving discs wear downequally and the areas of the surfaces of contact between the drivingdiscs and the driven disc remain substantially the same throughout thelife of the starter drive with the result that the starter drive has amuch longer life and more satisfactory operation than would be the caseif one driving disc were into the driven disc at a much greater ratethan the other driving disc.

When the engine becomes self operative and attains a speed such that thelinear speed of the driven disc 35 as effected by the engine exceeds thelinear speed of the driving discs 33 and 34 as effected by the startingmotor, driving engagement between the driving and driven discs of thestarter drive is automatically released. This is accomplished that dueto the fact that as the driven disc 35 tends to run ahead of the drivingdiscs 33 and 34 these driving discs tend to screw themselves along theirscrew threaded connections away from the driven discs. After the enginestarts the electromagnet is automatically deenergized by the opening ofthe automatic switch H0. The suction produced in the engine intake whenoperating will be sufficient to raise the diaphragm i l3 against theaction of the spring I I5, thereby separating contact I [4 from contactsI06 and I07. The spring 9! will then be released to effect movement ofthe parts 85, 82, 84 and Ill toward the right as viewed in Fig.2. Thespring 15 will also be released so as to move the upper end of the lever70 toward the right, returning it to its normal position. In this waythe engine starter drive parts are restored to normal position as shownin Figs. 1, 2, 3, and 10.

Since the ends of lever ll! bear yieldingly upon the sleeve flange 49,the internal flange 52 of sleeve 53 will bear yieldingly against thehelical splines 5| of the member 44. Therefore, since the sleeve 53 isyieldingly urged toward the left, the driving disc 33 will be yieldinglyurged against the driven disc 35; and, since the driving disc 34 iscaused to rotate by the sleeve 53 under the action of yielding pressure,the driving disc 34 will be yieldingly pressed against the driven disc35. Therefore both driving discs are urged by means independent of themotor against the driven disc with yielding pressure. This is desirablefor the purpose of compensating for wear of the friction surfaces of thedriving and driven discs. There is another purpose which is important.If the engine should make a weak or false start and fail to attain aspeed sufiicient to insure self operation, the spring 16, being thenheld under pressure greater than normal by the electromagnet, anactuating force is thereby stored in the spring '16 which tends tomaintain the preliminary contact between the driving discs and thedriven disc so that, if there is any tendency to relieve pressurebetween the driving and driven discs during a false or weak start of theengine, this tendency will be counteracted by the tendency of the spring15 to urge the driving discs almost instantaneously back intocooperative relation with the driven discs. In other words, the springit forms a function analogous to that performed in the conventionalone-way or overrunning clutch by the springs which are provided each forurging a clutch roller into wedging engagement between the clutch camand the clutch shell. Thus when the engine attempts to start on its ownpower and tends to release the driving engagement between the drivingand driven discs and then fails to attain a speed sufficient to maintainself operation, the starting motor drive is at all times ready to pickup the load of cranking the engine instantaneously.

The electromagnetic means which operates independent of the motor tocause the driving discs to be pressed against the driven disc before themotor is operated is not only a convenient means for preconditioning thestarter drive, but is one which is well adapted to cooperate with thestarter drive of this type. It requires a relatively small force to movethe driving disc 33 from its position shown in Fig. 10 to that shown inFig. 11 Where it engages the driven disc 35 and it requires asubstantially greater force to move the driving disc 34 into engagementwith the driven disc 35 and to effect compression of spring it beyondits normal state of compression. The electromagnetic device is Welladapted to provide the actuating forces which are required. At first theattraction upon the solenoid armature 32 is relatively small, but theforce required to move the driving disc 33 toward the left is relativelysmall. As the solenoid armature 82 approaches the core 83, theattraction increases greatly to give the necessarily greater forcerequired to move the driving disc 34 against the driven disc 35 and tocompress the spring 16 beyond its initial state. It is also necessarythat the starter switch contact be pressed against the stationarycontacts 95' and 91 with a pressure suihcient to insure a goodelectrical contact. The electromagnet is also well adapted to give thisfinal pressure which is needed between the starter contacts in thestarter switch. During final movement of the solenoid armature 82 towardthe left when the air gap between the armature and core is closing up,the pull upon the armature increases tremendously and is sufiicient notonly to efiect the desired movements of the engine starter drive, butalso to compress the spring 8? beyond its initial state of compressionand to force movable contact 95 firmly against the stationary contacts96 and Bl.

The electromagnet is so constructed as to effect a pull on the armature82 sufficient to make good electrical contact between the contacts inthe starter switch. The magnetic pull required for closing the switchproperly is greater than that suflicient for preconditioning the enginestarter drive prior to actual operation of the motor.

As undue pressure between the driving discs and the driven disc prior tooperation of themotor is as undesirable as insufiicient pressure, thespring 16 operates while the motor switch is closed to limit the forcewhich can be applied by the electromagnet to the shifting lever 19. Thespring 16 is so designed that upon being deflected a certain distance bythe armature 82 when closing the motor switch, the spring will exert theproper force uponthe lever 10, tending to rotate it clockwise about itspivotal connection with the link 84. In this way the spring 16 operatesnot only as a spring exerting yielding pressure upon the shifting collarflange 49 for the purposes herein specified, but spring 16 operates alsoas a means for limiting the amount of pressure which can be effected bythe electromagnet.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow:

What is claimed is as follows:

1. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, meansindependent of the motor for moving the driving discs against the drivendisc prior to operation of the motor, and independent drivingconnections between the shaft and driving discs, said connections each]including camming members whereby, in response to operation of the motorafter operation of said independent disc moving means, each driving discis urged against the driven disc with pressure suflicient for drivingengagement, and whereby, when the engine becomes self-operative, thedriving pressure will be relieved, and a connection between the twodriving discs for the purpose of equalizing the pressure exerted by thedriving discs upon the driven disc, said connection being so constructedand arranged that relative rotation between the driving discs and theshaft is concurrent and equal.

2. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, meansindependent of the motor for moving the driving discs against the drivendisc prior to operation of the motor, and independent drivingconnections between the shaft and driving discs, each of saidindependent connections being so constructed and arranged that, inresponse to operation of the motor after operation of said independentdisc moving means, the pressure between each driving disc and the drivendisc will be increased and that said pressure will be relieved when theengine becomes self-operative and a connection between the two drivingdiscs for the purpose of equalizing the pressure exerted by the drivingdiscs upon the driven disc, said connection .being so constructed andarranged that relative rotation between the driving discs and the shaftis concurrent and equal.

3. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, meansindependent of the motor for moving the driving discs against the drivendisc prior to operation of the motor, and independent drivingconnections between the shaft and driving disc, each of said independentconnections being such that relative rotation between a disc and theshaft causes relative axial movement between them whereby, in responseto operation of the motor after operation of said independent discmoving means, each driving disc is urged against the driven disc withpressure sufficient for driving engagement, and whereby, when the enginebecomes self-operative, the driving pressure will be relieved, and aconnection between the two driving discs for the purpose of equalizingthe pressure exerted by the driving discs upon the driven disc, saidconnection being so constructed and arranged that relative rotationbetween the driving discs and the shaft is concurrent and equal.

4. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, meansindependent of the motor for moving the driving discs against the drivendisc prior to operation of the motor, and independent drivingconnections between the shaft and driving discs, said independentconnections being screw-threads, respectively, of opposite pitchwhereby, in response to operation of the motor after operation of saidindependent disc moving means, each driving disc is urged against thedriven disc with pressure suflicient for driving engagement, andwhereby, when the engine becomesself-operative, the driving pressurewill be relieved, and a connection between the two driving discs for thepurpose of equalizing the pressure exerted by the driving discs upon thedriven disc, said connection being so constructed and arranged thatrelative rotation between the driving discs and the shaft is concurrentand equal.

5. In an engine starter, the combination of a drivendisc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, independentdriving connections between the shaft and driving discs so constructedand arranged that relative rotation between a disc and the shaft causesrelative axial movement between them, and means independent of the motorfor moving one of the driving discs axially into engagement with thedriven disc and for causing the other driving disc to rotate in suchdirection relative to the shaft that said other driving disc will bemoved axially against the driven disc, and a connection between the twodriving discs so constructed and arranged that the turning of the secondmentioned driving disc relative to the shaft is accompanied by an equalamount of turning of the first mentioned driving disc relative to theshaft, whereby the shaft together with the second mentioned driving discadvances axially toward the driven disc, the first mentioned drivingdisc then being aXiallyrestrai-ned by the driven disc.

6. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, independentdriving connections between the shaft and driving discs so constructedand arranged that relative rotation between a disc and the shaft causesrelative axial movement between them, and means independent of the motorfor moving the shaft axially thereby moving one of the driving discsaxially into engagement with the driven disc and for causing the otherdriving disc to rotate in such direction relative to the shaft that saidother driving disc will be moved axially against the driven disc, and aconnection between the two driving discs so constructed and arrangedthat the turning of the second mentioned driving disc relative to theshaft is accompanied by an equal amount of turning of the firstmentioned driving disc relative to the shaft, whereby the shaft togetherwith the second mentioned driving disc advances axially toward thedriven disc, the first mentioned driving disc then being axiallyrestrained by the driven disc.

7. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a shaft driven by the motor, independentdriving connections between the shaft and driving discs so constructedand arranged that relative rotation between a disc and the shaft causesrelative axial movement between them, and means independent of the motorfor moving one of the driving discs axially into engagement with thedriven disc, said means including a shifter sleeve having a helicalspline connection with the other driving disc for causing said otherdisc to rotate in such direction relative to the shaft that said otherdriving disc will be moved axially against the driven disc, and aconnection between the two driving discs so constructed and arrangedthat the turning of the second mentioned driving disc relative to theshaft is accompanied by an equal amount of turning of the firstmentioned driving disc relative to the shaft, whereby the shaft togetherwith the second mentioned driving disc advances axially toward thedriven disc, the first mentioned driving disc then being axiallyrestrained by the driven disc.

8. In an engine starter, the combination of a driven disc connected withthe engine, driving discs located respectively on opposite sides of thedriven disc, a starting motor, a main shaft driven by the motor, atubular shaft mounted on the main shaft and having a longitudinal-splineconnection therewith, a spring for urging the tubular shaft in onedirection, driving discs supported by the main shaft and each having ascrew-thread connection with the tubular shaft, a shifter sleeve havinga helical spline connection with one of the driving discs and alongitudinal spline connection with the tubular shaft, said springurging said sleeve into a certain position relative to the driving discwith which it is associated, and means for moving the sleeve, and aconnection between the two driving discs so constructed and arrangedthat the turning of the second mentioned driving disc relative to thetubular shaft is accompanied by an equal amount of turning of the firstmentioned driving disc relative to the tubular shaft, whereby thetubular shaft together with the second mentioned driving disc advancesaxially toward the driven disc, the first mentioned driving disc thenbeing axially restrained by the driven disc.

9. For use in a starter for an engine having a friction driven disc, thecombination of a shaft adapted to be connected with a starting motor andto be driven thereby, friction driving discs mounted upon said shaft andadapted to engage with opposite sides of the driven disc of the engine,independent driving connections between the shaft and driving discs,said connections each including camming members whereby, in response tooperation of the motor following preliminary movement of the drivingdiscs into engagement with the engine disc, each driving disc is urgedagainst the engine disc with pressure suificient for driving engagement,and whereby, when the engine becomes self-operative, the drivingpressure will be relieved, longitudinal spline connections between thedriving discs whereby rotation of one driving disc relative to the shaftis accompanied by an equal amount of rotation of the other driving discrelative to the shaft, and driving disc shifting means adapted foractuation independent of the motor and including a member, supported bythe shaft and movable longitudinally thereof and provisions responsiveto movement of said member in one direction for causing preliminarymovement of said driving discs into engagement with the engine disc.

10. For use in a starter for an engine having a friction driven disc,the combination of a shaft adapted to be connected with a starting motorand to be driven thereby, friction driving discs mounted upon said shaftand adapted to engage with opposite sides of the driven disc of theengine, independent screw-thread connections of opposite pitch,respectively, between the shaft and driving discs, longitudinal splineconnections between the driving discs whereby rotation of one drivingdisc relative to the shaft is accompanied by an equal amount of rotationof the other driving disc relative to the shaft, and driving discshifting means adapted for actuation independent of the motor andincluding a member, supported by the shaft and movable longitudinallythereof and provisions responsive to movement of said member in onedirection for causing preliminary movement of said driving discs intoengagement with the engine disc.

11. For use in a starter for an engine having a friction driven disc,the combination of a shaft adapted to be connected with a starting motorand to be driven thereby, friction driving discs mounted upon said shaftand adapted to engage with opposite sides of the driven disc of theengine, independent screw-thread connections of opposite pitch,respectively, between the shaft and driving discs, longitudinal splineconnections between the driving discs whereby rotation of one drivingdisc relative to the shaft is accompanied by an equal amount of rotationof the other driving disc relative to the shaft, a shifter sleevecarried by the shaft and having a helical spline connection with one ofthe driving discs and a longitudinal spline connection with the shaft,and a spring urging said sleeve into a certain position relative to thedriving disc with which it is associated.

12. For use in a starter for an engine having a friction driven disc,the combination of a shaft adapted to be connected with a starting motorand to be driven thereby, friction driving discs mounted upon said shaftand adapted to engage with opposite sides of the driven disc of theengine, independent driving connections between the shaft and drivingdiscs, each of said independent connections being such that relativerotation between a disc and the shaft causes relative axial movementbetween them whereby, in response to operation of the motor afteroperation of said independent disc moving means, each driving disc isurged against the driven disc with pressure suificient for drivingengagement, and whereby, when the engine becomes self-operative, thedriving pressure will be relieved, longitudinal spline connectionsbetween the driving discs whereby rotation of one driving disc relativeto the shaft is accompanied by an equal amount of rotation of the otherdriving disc relative to the shaft, a shifter sleeve carried by theshaft and having a helical spline connection with one of the drivingdiscs and a longitudinal spline connection with the shaft, and a springurging said sleeve into a certain position relative to the driving discwith which it is associated.

13. In an engine starter drive, a shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite side faces of a driven disc connected withthe engine to be started, screw-thread means of equal lead but ofopposite pitch respectively connecting the driving discs with the shaft,and longitudinal spline connections between the driving discs.

14. In an engine starter, a tubular shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite side faces of a driven disc connected withthe engine to be started, sleeves respectively connected with thedriving discs and located respectively within and surrounding thetubular shaft, and screw thread means of equal lead but of oppositepitch re spectively connecting the sleeves with the shaft.

15. In an engine starter, a tubular shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite side faces of a driven disc connected withthe engine to be started, sleeves respectively connected with thedriving discs and located respectively within and surrounding thetubular shaft, screw thread means of equal lead but of opposite pitchrespectively connecting the sleeves with the shaft, and longif tudinalspline connections between the driving discs.

16. In an engine starter, a tubular shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite sidefaces of a driven disc connected with theengine to be started, sleeves respectively connected with the drivingdiscs and located respectively within and surrounding the tubular shaft,screw thread means of equal lead but of opposite pitch respectivelyconnecting the sleeves with the shaft, said screw thread means eachcomprising a helical row of balls cooperating with helical ball racesprovided respectively by the shaft and by thesleeve of a driving disc.

17. In an engine starter drive, a shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite side faces of a driven disc connected withthe engine to be started, screw-thread means of equal lead but ofopposite pitch respectively connecting the driving discs with the shaft,longitudinal spline connections between the driving discs, a Shiftersleeve having a longitudinal spline connection with the shaft and ahelical spline connection with one of the by an operating member for thepurpose of mov-' ing the driving discs into engagement with the drivendisc preliminary to the operation of the starting motor, the saidhelical spline connection being such that, after the shifter sleeve hasbeen moved to cause one of the driving discs to engage the driven disc,further movement of the shifter sleeve in the same direction will causethe other driving disc to approach against the driven disc, and a springfor restoring the shifter sleeve to its normal position relative to thedrivging discs, and the driving discs to normal position spaced from thedriven disc. '18. In an engine starter, a tubular shaft mounted foraxial and rotary movement and adapted to be driven by a starting motor,driving discs adapted to engage opposite side faces of a driven discconnected with the engine to be started, sleeves respectively connectedwith the driving discs and located respectively within and surroundingthe tubular shaft, screw thread means of equal lead but of oppositepitch respectively connecting the sleeves with the shaft, a shiftersleeve having a longitudinal spline connection with the shaft and ahelical spline connection with one of the driving discs and adapted tobe moved axially by an operating member for the purpose of moving thedriving discs into engagement with the driven disc preliminary to theoperation of the starting motor, the said helical spline connectionbeing such that, after the shifter sleeve .has been'moved to cause oneof the driving discs to engage the driven disc, further move ment of theshifter sleeve in this same direction will cause the other driving discto approach against the driven disc, and a spring for restoringtheshifter sleeve to its normal position relative to the driving discs, andthe driving discs to normal position spaced from the driven disc.

19. In an engine starter, a tubular shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engageopposite side faces of a driven disc connected with theengine to be started, sleeves respectively connected with the drivingdiscs and located respectively within and surrounding the tubular shaft,screw thread means of equal lead but of opposite pitch respectivelyconnecting the sleeves with the shaft, longitudinal spline connectionsbetween the driving discs, a shifter sleeve having a longitudinal splineconnection with the shaft and a helical spline connection with one ofthe driving discs and adapted to be, moved axially by an operatingmember for the purpose of moving the driving discs into engagement withthe driven disc preliminary to the. operation of the starting motor, thesaid helical spline connection being such that, after the shifter sleevehas been moved to cause one of the driving discs to engage the drivendisc, further movement of the shifter sleeve in the same direction willcause the other driving disc to approach against the driven disc, and aspring for restoring the shifter sleeve to its normal position relativeto the driving discs, and the driving discs to normal position spacedfrom the driven disc.

'20. In an engine starter, a tubular shaft mounted for axial and rotarymovement and adapted to be driven by a starting motor, driving discsadapted to engage opposite side faces of a driven disc connected withthe engine to be started, sleeves respectively connected with thedriving discs and located respectively within and surrounding thetubular shaft, screw thread driving discs and adapted to be movedaxially means of equal lead but of opposite pitch respectivelyconnecting the sleeves with the shaft, said screw thread means eachcomprising a helical row of balls cooperating with helical ball racesprovided respectively by the shaft and by the sleeve of a driving disc,a shifter sleeve having a longitmhnal spline connection with the shaftand a helical spline connection with one of the driving discs andadapted to be moved axially by an operating member for the purpose ofmoving the driving discs into engagement with the driven discpreliminary to the operation of the starting motor, the said helicalspline connection being such that, after the shifter sleeve has beenmoved to cause one of the driving discs to engage the driven disc,further movement of the shifter sleeve in the same direction will causethe other driving disc to approach against the driven disc, and a springfor restoring the shifter sleeve to its normal position relative to thedriving discs, and the driving discs to normal position spaced from thedriven disc.

21. For use with an engine starter having a starting motor and operatingshaft driven by said motor, a starter drive for connecting the startingmotor in driving relationship with the engine flywheel, and comprising apair of driving discs operable to engage opposite sides of a driven discconnected to the engine flywheel, said driving discs adapted to besupported and operated by the shaft of the starting motor and providedwith means adapted to be operated by means independent of the startershaft to shift said driving discs into engagement with the driven discindependently of the starting motor shaft, independent operatingconnections whereby said driving discs may be operated from the startingmotor shaft, said connections including camming members whereby thedriving discs may be urged against the driven disc with sufficientpressure to drive said driven disc and whereby when the engine begins tooperate under its own power the driving discs will be released from thedriven disc, and a connection between the two driving discs soconstructed as to equalize the pressure adapted to be exerted by saiddiscs on the driven disc.

22. For use with an engine starter having a starting motor and operatingshaft driven by said motor, a starter drive for connecting the startingmotor in driving relationship with the engine flywheel, and comprising apair of driving discs operable to engage opposite sides of a driven discconnected to the engine flywheel, said driving discs adapted to besupported and operated by the shaft of the starting motor and providedwith means adapted to be operated by means independent of the startershaft to shift said driving discs into engagement with the driven discindependently of the starting motor shaft, independent operatingconnections whereby said driving discs may be operated from the startingmotor shaft, said connections including camming members whereby thedriving discs may be urged against the driven disc with suficientpressure todrive said driven disc and whereby when the engine begins tooperate under its own power the driving discs will be released from thedriven disc, and a connection between the two driving discs soconstructed as to equalize the pressure adapted to be exerted by saiddiscs on the driven disc, and longitudinal spline connections betweenthe driving discs.

23. In an engine starter, the combination of a starting-motor-operatedshaft, a pair of driving discs adapted for engagement with oppositefaces of a driven disc connected with the engine to be started andadapted to be rotated by said shaft, a tubular member surrounding saidshaft and providing one of the driving discs, a second tubular memberalso surrounding the shaft and providing the other driving disc, andmeans for effecting relative axial movement between said driving discsin response to rotary movement of the shaft, said means includingcamming means formed upon the outer surface of one tubular member andinner surface of the other, and

cooperating camming means operated by said shaft, the several cammingmeans being so constructed and arranged that the driving discs are heldin engagement with the driven disc with suificient pressure to preventany release of the driven disc during engine cranking, but will permitrelease of the driven disc when the engine begins to run under its ownpower.

24. In an engine starter, the combination of a starting-motor-operatedshaft, a pair of driving discs adapted for engagement with oppositefaces of a driven disc connected with the engine to be started andadapted to be rotated by said shaft, a tubular member surrounding saidshaft and providing one of the driving discs, a second tubular memberalso surrounding the shaft and providing the other driving disc, andmeans for effecting relative axial movement between said driving discsin response to rotary movement of the shaft, said means includinghelical threads formed upon the outer surface of one tubular member andinner surface of the other and cooperating threads on a member driven bysaid shaft, the means for effecting axial movement being so constructedand arranged that the driving discs are held in engagement with thedriven disc with sufficient pressure to prevent any release of thedriven disc -during engine cranking, but will permit release of thedriven disc when the engine begins to run under its own power.

25. In an engine starter, the combination of a starting-motor-operatedshaft, a pair of driving discs adapted for engagement with oppositefaces of a driven disc connected with the engine to be started andadapted to be rotated by said shaft, a tubular member surrounding saidshaft and providing one of the driving discs, a; second tubular memberalso surrounding the shaft and providing the other driving disc, andmeans for effecting relative axial movement between said driving discsin response to rotary movement of the shaft, said means includingcamming means formed upon the outer surface of one tubular member andinner surface of the other, a third member rotatable with the motorshaft and provided with camming means cooperating with the previouslymentioned camming means, all of said camming means being so constructedand arranged that the driving discs are held in engagement with thedriven disc with sufficient pressure to prevent any release of thedriven disc during engine cranking, but will permit release of thedriven disc when the engine begins to run under its own power.

26. In an engine starter, the combination of a starting-motor-operatedshaft, a pair of driving discs adapted for engagement with oppositefaces of a driven disc connected with the engine to be started andadapted to be rotated by said shaft, a tubular member surrounding saidshaft and providing one of the driving discs, a second tubular memberalso surrounding the shaft and providing the other driving disc, andmeans for effecting relative axial movement between said driving discsin response to rotary movement of the shaft, said means includinghelical threads formed upon the outer surface of one tubular sleeve andinner surface of the other, a third member rotatable with the motorshaft and provided with threads cooperating. with threads on bothtubular members, all of said threads having bearing bails receivedtherein.

27. In an engine starter, the combination of a starting-motor-operatedshaft, a pair of driving discs adapted for engagement with oppositefaces of a driven disc connected with the engine to be started andadapted to be rotated by said shaft, a tubular member surrounding saidshaft and providing one of the driving discs, a second tubular memberalso surrounding the shaft and providing the other driving disc, andmeans for eifecting relative axial movement between said driving discs,in response to rotary movement of the shaft, said means includinghelical threads formed upon the outer surface of one tubular sleeve andinner surface of the other, a third member rotatable with the motorshaft and provided with threads cooperating with threads on both tubularmembers, all of said threads being so constructed and arranged that thedriving discs are held in engagement with the driven disc withsuflicient pressure to prevent any release of the driven disc duringengine cranking, but will permit release of the driven disc when theengine begins to run under its own power.

28. For use in an engine starting apparatus having a starting motoradapted to operate the engine to be started, a starter drive throughwhich said motor operates the engine and having in combination, a pairof driving discs adapted for engagement with opposite faces of a drivendisc connected with the engine and rotatable by the shaft of thestarting motor, tubular members surrounding the starting motor shaft andproviding the driving discs, a third tubular member also surrounding thestarting motor shaft and means whereby rotation of said third tubularmember effects relative axial movement between said driving discs inresponse to rotary movement of the starting motor shaft, said meansincluding helical threads having bearing balls received therein andformed upon the inner and outer surfaces of the third tubular member andthe corresponding surfaces, of the other tubular members, and soconstructed and arranged that the driving discs are held in engagementwith the driven disc during the engine crankinig operation withsufiicient pressure to prevent any release of the driven disc but willpermit release of the driven disc when the engine begins to run underits own power, and said starter drive having means adapted to be actedupon by a force other than that of the starting motor to effect aninitial movement of said driving discs for engagement with said drivendisc.

7 JOHN B. DYER.

